Laser light of wavelength lambda passes through a thin slit of width a and produces its first dark fringes at angles of +/- 30 degree with the original direction of the beam. the slit is then reduced in size to a circle of diameter a. when the same laser light is passed through the circle, the first dark fringe occurs at

a) +/- 66.9 degree.
b) +/- 45.0 degree.
c) +/- 37.6 degree.
d) +/- 36.6 degree.
e) +/- 15.0 degree.

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.